1. Field of Invention
The present invention relates to a gas generator for a restraining device such as an airbag system for a vehicle.
2. Description of Related Art
A gas generator is used in an airbag apparatus and the like of a vehicle in order to actuate a restraining device. As such a gas generator, a pyrotechnic gas generator using a solid gas generating agent, a stored-type gas generator using pressurized gas, and a hybrid gas generator using both a solid gas generating agent and pressurized gas, are known. The pyrotechnic gas generator has a mechanism in which combustion gas is generated by actuating an ignition device and burning the gas generating agent charged in a housing. Therefore, the gas generating agent needs to be reliably and promptly ignited by the ignition device and burned. The ignition/combustion performance of the gas generating agent has an impact on the performance of the pyrotechnic gas generator.
As to the restraining device, the time from when a collision of a vehicle is detected till when the restraining device is actuated is extremely short. The pyrotechnic gas generator needs to facilitate ignition or combustion of the gas generating agent because discharge of combustion gas has to be started or ended immediately after the actuation of the ignition device.
It is known to adjust the positions, the number and the opening surface area of communication nozzles, that communicate an ignition chamber accommodating an ignition device and a combustion chamber charged with a gas generating agent. However, there remains room to investigate how combustion products (high-temperature gas and flame), which are generated from the ignition device, should act on the gas generating agent after being discharged to the combustion chamber through the communication nozzles (i.e., how the combustion products flow inside the combustion chamber).
In the inflator 100 disclosed in U.S. Pat. No. 5,458,371, the diffuser cover 104 and the annular base 106 are combined to form a housing.
An inner cylinder 120 provided with an ignition chamber wall hole (an ignition port) 130 is disposed inside the housing, wherein an internal space and an external space of the inner cylinder 120 are communicated with each other by the ignition chamber wall hole 130.
The ignition chamber wall hole 130 is formed to face a circular annular base 106 (i.e., downward) in the combustion chamber, so that combustion products that are generated from an ignition squib 126 or an enhancing agent (a charge) 128 are directed in the direction of the arrow shown in FIGS. 1-3 and brought into contact with a gas generant material 108. Note that a filter 134 surrounds the gas generant material 108.
According to JP-A No. 2007-131254, flow of gas discharged from the inside of a cylindrical partition wall 19 is divided into either ends in the axial direction by the cylindrical partition wall 19 partitioning the combustion chamber, and the combustion gas is caused to pass through a top filter and a bottom filter. The obliquely protruding openings 22a, 22b are formed in a circumferential wall portion of the cylindrical partition wall 19, in order to restrict the direction of gas flow.